Method of making a weighted golf swing trainer

ABSTRACT

A method of making at least two types of weighted golf swing trainers. In a first type of trainer club, a lower section of a hollow golf shaft is filled within a first type of particle and a flowable material. A barrier is then by created to keep the flowable material and the first type of particle in the lower section. A second type of particle and a compressible epoxy resin is placed into an upper section of the golf shaft so that the resin cures to surround the second type of particles. A method of making a second type of trainer club where flowable materials are impermissible. Such second club is made in a similar manner as the first type with the exception that the first type of particle and flowable material are mixed with compressible epoxy resin and placed into the lower section of the golf shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation-in-part of utility patent application Ser. No. 10/850,079 filed on May 19, 2004, and hereby claims the benefit thereof.

BACKGROUND OF THE INVENTION

The present invention relates to golf swing practice equipment and a method of making the same.

There are many golf swing trainers in the marketplace which claim to help golfers have a correct swing on a consistent basis. Exemplary of such golf swing trainers is that described in Sorenson U.S. Pat. No. 5,582,407.

Also, more than one year ago I invented and sold the golf swing trainer described in U.S. Provisional Application Ser. No. 60/384,502 filed May 29, 2002.

Existing golf swing trainers suffer from one or more disadvantages, including:

-   -   Inability to actually hit a golf ball with the trainer to         provide feedback to the golfer as to the effectiveness of the         golfer's swing.     -   Failure to meet USGA® compliant requirements for on course use.     -   Lack of the “feel” of an actual golf club.

A large portion of the existing prior art patents relating to golf clubs involve designs that allow users to selectively adjust the golf club while playing, thereby altering the swing weight, sweet spot, or some other characteristic. In this respect, such clubs are intended to help a user overcome their own deficiencies. However, such clubs are generally distinguishable from weighted golf swing trainers because trainer clubs are designed to help a golfer learn proper form and enhance other characteristics of their swing. Thus, the technologies relating to user-modifiable golf clubs is often times incompatible with the objective and intended use of trainer clubs.

Although the use of flowable materials in golf clubs has been used in the past, such use of flowable materials appear to be limited to use in standard golf clubs, specifically those which aim to provide a user with selectable adjustments while on the golf course. For example, in U.S. Pat. No. 5,082,279 issued to Hull on Jan. 21, 1992, a golf club is disclosed that appears to provide for selectable adjustments to standard golf clubs by shifting weight throughout the entire shaft thereof via a series of valves. By doing so, a user may adjust the swing weight and balance weight of the club. Such a design fails to disclose a flowable material limited to the lower section of the golf club.

Golf clubs have also used two different particles, heavy and light, to desirably weight the club head. For example, in U.S. Pat. No. 4,145,052 issued to Janssen on Mar. 20, 1979, a golf club is disclosed that allows for selective adjustments to the club head, for the purpose of altering the location of the sweet spot. By using two types of materials, the swing weight or balance weight of the club head is maintained. Such a design is distinguishable from the present invention in that sweet spot alterations in a club head are primarily for users who hit off-center and may wish to adjust the sweet spot according to their personal style and/or deficiencies. Such technology is not applicable to disposing two different particles in the shaft of a golf club since sweet spots may not be altered by modifications to the shaft.

There are also patents that disclose the use of weights that are interchangeable between the golf club head and the shaft. For example, U.S. Pat. No. 3,606,327 issued to Gorman on Sep. 20, 1971 discloses a golf club that provides apertures for receiving a capsule in both the golf club head and the shaft. The capsule includes a plurality of weighted washers that maybe selectively added or removed by the user. The capsule is interchangeable between the shaft and the club head. Such a design is provided for, once again, altering the swing weight of the club, which in turn alters the balance point of the club. Such alteration of the balance point is typically disadvantageous in golf swing trainers since it is the preset placement of the balance point that provides part of the advantageous training features.

The present invention is directed to a weighted golf swing trainer that overcomes deficiencies of these prior golf clubs and prior golf swing trainers.

SUMMARY OF THE INVENTION

A golf swing trainer according to the present invention comprises a shaft having a grip end and a head end, and a weighted filling inside the shaft. The weighted filling comprises a first size of high density particles with interstices between them and tungsten powder in a lower section, and a second type of high density particles in an upper section, the lower section being closer to the head end and is the upper section. The high density particles typically have a density of at least 8 g/cc and are spheroidal; preferably they are lead shot. The two types of particles can be of the same material or different materials, and can have the same size or different size. So the trainer can be used as a regular golf club, it can have a grip on the grip end of the shaft and a club head on the head end of the shaft.

So that the trainer has the feel of a regular golf club during the swing, the filling material can include urethane resin. In one version of the invention there is cured urethane resin only in the upper section. So that the urethane resin is only in the upper section, there is a liquid impermeable barrier between the two sections.

In one version of the invention, the tungsten powder can move during the swing, to help the user swing properly. This can be effected by having the tungsten powder be present in only a portion of the lower section.

For a club that is useable on the golf course, according to the United States Golf Association (“USGA®”) it is not permissible to have any moving parts. In an alternate version of the invention satisfying USGA® requirements, there is no barrier and there is cured polymeric material, such as urethane resin, along the length of the shaft, wherever there are particles to prevent the particles from moving during a swing.

Another benefit of using the improved golf swing trainer club is that proper and consistent use of the trainer club promotes building muscles specifically exerted when a user swings the club in the proper swing plane. These muscles, the so-called “golf muscles,” include muscles surrounding the arms, hips and legs. Of these muscles, there are those generally known as “slow-twitch” muscles that are used primarily when the muscle must support a large amount of weight for an extended period of time. An example of these muscles are those exerted when curling weights with the arms. There are also muscles known as “fast-twitch” muscles that are used for quick bursts of power, such as the leg muscles exerted by sprinting runners. Advantageously, the golf swing trainer made according to the present invention helps build the “fast-twitch” muscles used in the golf swing. By promoting users to swing the club in the proper swing plane, the fast-twitch muscles typically used when swinging in this plane are exercised. Incorporating a series of exercises with the club can yield significant muscle-building benefits that are targeted to the “fast-twitch” muscles, yielding a significant increase in swing speed. Moreover, a unique advantage in building “fast-twitch” muscles with the golf swing trainer made according to the present invention is that the user, by increasing club head or swing speed, in turn receives a dramatic increase in distance, which is a long-felt need.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention could be better understood with reference to the following description, appended claims, and accompanying drawings where:

FIG. 1 is a front elevation view of swing trainer embodying features of the present invention;

FIG. 2 is a transverse, partial sectional view of the swing trainer of FIG. 1 taken on line 2-2 in FIG. 1;

FIG. 3 is a transverse, partial sectional view of the swing trainer of FIG. 1 taken on line 3-3 in FIG. 1;

FIG. 4 is a flowchart illustrating a method of making a weighted golf swing trainer; and

FIG. 5 is a flowchart illustrating an method of making an alternate embodiment of a weighted golf swing trainer.

The drawings are not to scale.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1-3, a swing trainer 10 according to the present invention comprises a shaft 12 having a wall 13, a head end 14 and a grip end 16, with a grip 18 mounted on the grip end 16 and a golf club head 20 mounted on the head end 14.

The shaft is hollow substantially along its entire length. For the reasons detailed below, the grip end 16 needs to be hollow. The bottom portion of the lower end need not be hollow.

The shaft 12 can be made of any material conventionally used for golf clubs, such as a steel, graphite or tungsten alloy. The shaft 12 can be a substantially constant diameter, but preferably is tapered, with a larger diameter at the grip end 16 then at the head end 14. For example, the outside diameter of the grip end 16 can be about 9/16 inch, and the outside diameter of the head end 14 can be about 5/16 inch.

The golf club head 20 can be any head conventionally used on golf clubs. It can be an iron, a wedge, or a driver. It typically is not a putter head.

The grip 18 can be any conventional golf club grip. Optionally, it can be a training grip which is configured to require the golfer place his or her hands in a proper position for an effective golf swing.

There is a weighted filling inside of the shaft 12 in a lower section 32 of the shaft 12 the filling can comprise a first size of lead shot 34 and tungsten powder 36.

In an upper section 42 of the shaft 12, the filling can comprise a second size of lead shot 44 and cured epoxy resin 46. The lower section 32 is closer to the head end 14 than is the upper section 42. The size of the lead shot 34 and 44 can be the same, but preferably the first size 34 is of larger diameter than the second size 44 to accommodate the tungsten powder 36 in interstices.

The length of the lower section 32 can be about 8 to about 16 inches, and preferably is about 12 to about 14 inches.

Typically, the lower section 32 has size 5 shot which has an average diameter of 0.12 inches. Preferably, the lead shot used in the upper section 42 is a size 8 or 10 lead shot, which has an average outside diameter of 0.09 inch and 0.07 inch, respectively. More than one size of lead shot can be used in either or both sections.

A preferred tungsten powder has a tab density of at least 9 g/cc. A preferred powder is available from Tungsten Heavy Powder, Inc. of San Diego, Calif. under the name “Technon® Ultra Powder.” This spheroidal powder comprises 98%-99% tungsten, with a tab density according to ASTM spec 527 of at least 10-11 g/cc; a particle size of 30-100 microns; and a flowability according to ASTM spec B212 of 7.2 seconds. This powder is prepared from sintered tungsten parts with a higher density than virgin tungsten powder. The tungsten powder typically can be size 100 mesh. However, it is recognized that other types of tungsten powder or other weighted flowable material may be substituted for the above so long as it is capable of flowing through the interstices created by the first type of particle, i.e. lead shot 34.

The tungsten powder 36 fills a portion of the lower section, typically only about half of it, so that the tungsten powder can move during the golf swing shift position. That is why larger diameter lead shot with more void space is used in the lower section. This helps a golfer perform a proper wrist cock, which adds distance to the golfer's shot.

Also, the lower section need not be completely filled with lead shot 34 so that the lead shot can also move in the lower section during a swing.

There is a barrier or gasket 52 between the lower section 32 and upper section 42. Preferably, the barrier 52 is liquid impervious. It can be made out of cork covered with cloth, vinyl or rubber material, or wadded up tissue paper. Its purpose is to keep uncured resin from reaching the lower section 32.

Cured polymeric material, such as SBR rubber, “Kraton™” material, or polyurethane resin, can be part of the filling material. Preferably polyurethane resin 46 is cured in situ and provides a high “rebound effect” so that the club has a realistic feel. It can have a Shore A hardness of about 80. A suitable preferred polyurethane is available from Cytec Industries, Inc. of Olean, N.Y. under the product name “Conathane®” TU-6080. This preferred polyurethane has a viscosity at 25° C. of about 2600 cps before cure; a tensile strength of about 2025 psi; 100% modulus of about 610; 300% modulus of about 1550, an elongation of about 350%; and a tear strength of about 275 pli. An even more preferable polyurethane is available from Conap, Inc., a division of Cytec Industries, Inc. under the product name “Conathane®” TU-8070. This polyurethane has viscosity of 1000 cps at 25° C. before cure; a tensile strength of about 1500 PSI; 100% modulus of about 550 PSI; 300% modulus of about 800 PSI; an elongation of about 750%; a tear strength of about 280 lbf/in; and Shore A hardness of about 70. It is recognized that other compressible polyurethane resins and may also be used so long as the resin maintains a high “rebound effect” after curing.

The weight system is designed so that the balance point of the trainer is not at its center, but is closer to the head end 14 than the grip end 16. Preferably the balance point is from about 2 to about 4 inches closer to the head end 14 than it is to the grip end 16. This approximates the feel of a regular golf club.

As shown in FIG. 4, a method of making the swing trainer 10 is described. To manufacture the swing trainer 10, the first step 200 is to select a hollow shaft 12 is selected that has an upper section 42, a lower section 32, a grip end 16, and a head end 14. In the next step 202, a first type of particle, preferably lead shot 34, is placed in the lower section 32 of the shaft 12, whereby there interstices between the particles 34. Next 204, a flowable material, preferably tungsten powder 36 as described herein, is placed in the lower section 32 of the shaft 12 to fill in at least some of the interstices. To help the lead shot 34 and flowable material 36 to travel down the shaft 12, a rubber mallet may be tapped against the shaft 12 to ensure that the lead shot 34 and flowable material 36 traveled down to the bottom. To keep the lead shot 34 and tungsten powder 36 from falling out of the bottom, in the next step 206, a barrier 52 is formed between the upper and lower sections 42 and 32. A plug or wadded tissue paper tamped down against the lead shot 34 and flowable material 36 can be used.

A small amount of uncured resin is then added, preferably about 2 squirts of the uncured resin 46 from a 400 ml two cartridge dispensing gun. Another 5 squirts of the uncured resin 46 should be added after waiting about two to three minutes. In the next step 208, a second type of particle 44 is placed in the upper section 42 of the shaft 12 which displaces the resin 46, while allowing the lead shot 44 to be surrounded on all sides by the resin 46. Preferably, only ¾ of the measured lead shot 44 should be placed in the upper section 42 first. After waiting for the mixture to settle, as illustrated in box 210, additional resin 46 is added to the upper section 42, preferably 2 squirts of uncured resin, and the remaining ¼ of lead shot 44 is then added. The resin is prepared by mixing components of the polyurethane resin. This process is repeated until the shaft is filled. The uncured resin is allowed to cure in situ. The grip 18 is then placed on the shaft. Preferably, a club head 20 is attached to the shaft 12 prior to filling with lead shot 34 so as to prevent adverse effects of back pressure that may occur when the golf club head 20 is attached subsequent to filling the shaft 12.

Optionally, there is an empty space between the top of the shot filling in the upper section 42 and the top of the shaft 12.

Each section can contain different types and different sizes of high density particles, allowing for a change in the weight position. However, such different sizes of particles may not be adjusted by the user.

In an alternate version of the invention, for a club that can be used on a golf course, it is necessary that the filling material not move during a stroke. In this version of the invention, polyurethane resin is used along the entire length of the shaft wherever there is filling material, and there is no barrier 52 in use. The high rebound polyurethane resin keeps the lead shot and tungsten from moving, cushions the weighting material, and provides a lively flexible shaft. Also, smaller size lead shot is used in the bottom section 32 to help prevent movement of the tungsten powder.

To manufacture such an alternative version, as shown in FIG. 5, a method of making such a club is illustrated. Notably, the process for making this embodiment is nearly identical to the method illustrated in FIG. 4 and described above with the exception of the preparing different materials for the lower section 32 of the shaft 12. More specifically, the after selecting a club as illustrated in box 300, in box 302, a mixture is formed with a first type of particle (lead shot), flowable material (tungsten powder), and compressible epoxy resin. This mixture is placed into the lower section 32 of the shaft 12 as illustrated in box 304. The mixture created by this process yields a static mixture that complies with USGA® rules. The remaining steps illustrated in boxes 306, 308, and 310 remain identical to that which is described in boxes 206, 208 and 210.

The present invention has significant advantages for a golfer including the following:

-   -   It is actually possible to hit the ball with the club to get         instant feedback on a swing.     -   The weight system forces, the golfer to swing properly on plane.     -   The correctly placed weight system places the golf swing on the         correct swing plane.     -   The shifting weight teaches the golfer a proper wrist cock         release.     -   The correct weighting, similar to a golfer's other clubs,         creates muscle memory for the correct swing path.     -   Creating the correct swing plane and allowing the golfer to see         the ball flight builds confidence, and ingrains a sub-conscious         repeatable swing memory.     -   The weighted club provides an excellent warmup before playing a         round of golf, just as a baseball hitter warms up with a         weighted bat in the on deck circle.     -   Because of the urethane system, the club has the feel of a         regular golf club when the ball is hit.     -   The shifting weight provides extra momentum at the bottom of the         swing, providing encouragement of the proper wrist release at         the bottom of the swing, which is not available with a solid         steel bar.     -   The use of different sized shot placed discretely inside the         shaft along with the resin provides the ability to adjust the         weight and feeling of the club that is not available with a         solid steel bar.     -   This discrete weighting allows the wrist cock and wrist release         to be varied, and to vary the feeling of the club according to         the abilities and swing speed of the golfer.     -   In the version of the invention where all of the filling         material is held in place by urethane resin, the club can         legally be used on the golf course, thus providing an         opportunity for an instant “tune up” for the golfer during a         round.

EXAMPLES Example 1 Preparing Seven Iron

-   -   A. Men's Seven Iron—A men's seven iron was prepared by placing         the following materials into a shaft in this order:     -   Lead shot, #5—4.5 ounces     -   Tungsten powder—2.8 ounces     -   Barrier     -   Lead shot, #8—14.1 ounces and polyurethane resin, two components         mixed, to fill the remaining shaft.

Preferably, a finished men's seven iron should measure approximately 36.5 inches in length and have a finished weight of approximately 2 pounds and 8 ounces. A properly manufactured club should have an exact center point of about 18.25 inches and a balance point of approximately 2.25 inches measured from the exact center toward the head end (plus or minus 0.5 inches).

-   -   B. Ladies Seven Iron—A ladies seven iron was prepared by placing         the following materials into a shaft in this order:     -   Lead shot, #5—2.8 ounces     -   Tungsten powder—1.4 ounces     -   Barrier     -   Lead shot, #8—9.7 ounces and polyurethane resin, two components         mixed, to fill the remaining shaft.

Preferably, a finished ladies seven iron should measure approximately 35.5 inches in length and have a finished weight of approximately 2 pounds. A properly manufactured club should have an exact center point and balance point that is proportional that described in the men's club, subject to the reduced length of the ladies club.

Example 2 Preparing Driver

A. Men's Driver—A men's driver was prepared by placing the following materials into a shaft in this order:

-   -   Lead shot, #5—4 ounces     -   Tungsten powder—2.8 ounces     -   Barrier     -   Lead shot, #10—3.0 ounces     -   Lead shot, #5—10 ounces     -   Polyurethane resin, two components mixed, to fill the remaining         shaft while placing the lead shot above the barrier.

Preferably, a finished men's driver should measure approximately 44 inches in length and have a finished weight of approximately 2 pounds and 4 ounces. A properly manufactured club should have an exact center point of about 22 inches and a balance point of approximately 2.5 inches measured from the exact center toward the head end (plus or minus 0.5 inches). Such measurements assume that the club is being made with a training grip (ergonomic). Standard grips will result in clubs that are approximately 2 ounces lighter.

B. Ladies Driver—A ladies driver was prepared by placing the following materials into a shaft in this order:

-   -   Lead shot, #5—3.0 ounces     -   Tungsten powder—1.5 ounces     -   Barrier     -   Lead shot, #10—1.0 ounces     -   Lead shot, #5—8.1 ounces     -   Polyurethane resin, two components mixed, to fill the remaining         shaft while placing the lead shot above the barrier.

Preferably, a finished ladies driver should measure approximately 42 inches in length and have a finished weight of approximately 1 pound and 14 ounces. A properly manufactured club should have an exact center point and balance point that is proportional that described in the men's club, subject to the reduced length of the ladies club. Such measurements assume that the club is being made with a training grip (ergonomic). Standard grips will result in clubs that are approximately 2 ounces lighter.

Example 3 Wedge Legal for Use on a Golf Course

A. Men's Legal Wedge—A wedge legal for use on a golf course was prepared by placing the following materials into a shaft, in this order.

-   -   Lead shot, #10—5.5 ounces     -   Tungsten powder—3.5 ounces     -   Lead shot, #5—5.5 ounces

Preferably, a finished men's legal wedge should measure approximately 35 inches in length and have a finished weight of approximately 2.0 pounds. A properly manufactured club should have an exact center point of about 17.5 inches and a balance point of approximately 5.5 inches measured from the exact center toward the head end (plus or minus 0.5 inches). Such measurements assume that the club is being made with a training grip (ergonomic). Standard grips will result in clubs that are approximately 2 ounces lighter.

B. Ladies Legal Wedge—A wedge legal for use on a golf course was prepared by placing the following materials into a shaft, in this order.

-   -   Lead shot, #10—4.5 ounces     -   Tungsten powder—3.5 ounces     -   Lead shot, #5—4.5 ounces

Preferably, a finished ladies legal wedge should measure approximately 34 inches in length and have a finished weight of approximately 1 pound and 14 ounces. A properly manufactured club should have an exact center point and balance point that is proportional that described in the men's club, subject to the reduced length of the ladies club. Such measurements assume that the club is being made with a training grip (ergonomic). Standard grips will result in clubs that are approximately 2 ounces lighter.

It should be noted that standard steel lengths are used for each club, but the clubs are cut ⅛th inch short from the head end 14 of the shaft 12, which allows for sufficient space to install a grip and maintain stiffness.

In all examples, polyurethane resin was added slowly during the entire procedure, so that none of the filling material embedded in the resin moves during a swing, and provides a cushion of resin surrounding the lead shot to provide “life” to the club. In the case of the wedge, the resin allows the wedge to be usable on course.

Additionally, a preferable method of maintaining a good seal between the club head 20 and the shaft 12 is abrading the head end 14 with an abrasive, such as sandpaper. The inside of the club's hosel may also be abraded. The head end 14 and the hosel may both be cleaned with a solvent, such as Acetone. Each side is dried by using compressed air, and epoxy may then be applied to ensure a tight seal.

All features disclosed in the specification, including the claims, abstracts, and drawings, and all the steps in any method or process disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature disclosed in the specification, including the claims, abstract, and drawings, can be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Any element in a claim that does not explicitly state “means” for performing a specified function or “step” for performing a specified function, should not be interpreted as a “means” for “step” clause as specified in 35 U.S.C. § 112.

Although the present invention has been described in considerable detail with reference to the preferred versions thereof, other versions are possible. For example, instead of lead shot, steel shot or other high density material can be used. Therefore, the scope of the appended claims should not be limited to the descriptions of the preferred versions contained therein. 

1. A method for manufacturing a weighted golf swing trainer comprising the steps of: (a) selecting a hollow shaft having an upper section, a lower section, a grip end and a head end, the lower section being closer to the head end than is the upper section, the upper section between closer to the grip end than is the lower section; (b) placing a first type of particle in the lower section of the shaft and whereby there are interstices between the particles; (c) placing a flowable material in the lower section of the shaft to fill in at least some of the interstices; (d) forming a barrier between the upper and lower sections of the shaft; (e) placing a second type of particle in the upper section of the shaft; and (f) placing a compressible epoxy resin into the upper section of the shaft so that the resin cures to surround the second type of particle thereby.
 2. The method as in claim 1 wherein the flowable material is tungsten powder.
 3. The method as in claim 2 wherein the first type of particle is a different size than the second type of particle.
 4. The method as in claim 3 wherein the first and second types of particles are lead shot.
 5. The method as in claim 4 wherein the interstices formed between the particles of lead shot in step (a) are 8 g/cc.
 6. The method as in claim 1 wherein step (d), the barrier formed between the upper and lower sections of the shaft is a liquid impermeable barrier.
 7. The method as in claim 6 wherein step (d) further comprises the steps of: (1) placing the liquid impermeable barrier into the grip end; and (2) compressing the liquid impermeable barrier against the first type of particles and flowable material.
 8. The method as in claim 1 wherein after step (a) but before step (b), further comprising the step of attaching a golf club head to the head end.
 9. The method as in claim 8 wherein attaching the golf club head to the head end further includes the steps of: (1) abrading the head end; (2) cleaning the head end with a solvent; (3) drying the head end; (4) applying an adhesive to the head end and the golf head; and (5) inserting the head end into the golf head.
 10. The method as in claim 1 further comprising the step of: (g) attaching a grip to the grip end.
 11. A method for manufacturing a weighted golf swing trainer comprising the steps of: (a) selecting a hollow shaft having an upper section, a lower section, a grip end and a head end, the lower section being closer to the head end than is the upper section, the upper section between closer to the grip end than is the lower section; (b) mixing a first type of particle, a flowable material, and a compressible epoxy resin together to form a mixture therefrom; (c) placing the mixture in the lower section of the shaft; (d) forming a barrier between the upper and lower sections of the shaft; (e) placing a second type of particle in the upper section of the shaft; and (f) placing a compressible epoxy resin into the upper section of the shaft so that the resin cures to surround the second type of particle thereby.
 12. The method as in claim 11 wherein the flowable material is tungsten powder.
 13. The method as in claim 12 wherein the first type of particle is a different size than the second type of particle.
 14. The method as in claim 13 wherein the first and second types of particles are lead shot.
 15. The method as in claim 14 wherein the interstices formed between the particles of lead shot in step (a) are 8 g/cc.
 16. The method as in claim 11 wherein step (d), the barrier formed between the upper and lower sections of the shaft is a liquid impermeable barrier.
 17. The method as in claim 16 wherein step (d) further comprises the steps of: (1) placing the liquid impermeable barrier into the grip end; and (2) compressing the liquid impermeable barrier against the first type of particles and flowable material.
 18. The method as in claim 11 wherein after step (a) but before step (b), further comprising the step of attaching a golf club head to the head end.
 19. The method as in claim 18 wherein attaching the golf club head to the head end further includes the steps of: (1) abrading the head end; (2) cleaning the head end with a solvent; (3) drying the head end; (4) applying an adhesive to the head end and the golf head; and (5) inserting the head end into the golf head.
 20. The method as in claim 11 further comprising the step of: (g) attaching a grip to the grip end. 